Assig-nor to western electric com



Oct. 28. 1924. 1,512,907

R. D. CONWAY TELEPHONE SYSTEM Filed DSC- 29, 1919 4 SheetsSheet l //71 e/7/0/.' Ray 0 Conway 1,512,907 R. D. .CQNWAY TELEPHONE SYSTEM Filed Dec. 29, 1919 4 Sheets-Sheet 2 Mew/bf: Y Ray D. Conw y Oct. 28 I924. 1,512,907 R. D. CONWAY I :wzwraon! sums Fiiad a. 29. 1919 4 She'etsSheet 5 j .Y ill: L e

1 RBI Patented Oct. 28, 1924.

UNITED STATES PATENT OFFICE.

ROY I). CONWAY, OF CHATI-IAM, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NER YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application filed December 29, 1919.

To all whom it may concern: 7

Be it known that I, ROY D. CONWAY, a citizen of the United States, residing at Chatham, in the county of Morris and State of New Jersey, haveinvented certain new and useful In'iprovements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to an improved method and means for signaling over transmission lines and has particular reference to such method and means as applied to telephone systems.

Toll signaling systems have been devised wherein physical and phantom lines are employed for interconnecting distant offices or subscribers. In such systems, certain of the lines are-employed for the transmission of various signals, from one distant office, utilized to signal an operator at the other distant oflice and to control the: op-

eration of telephone repeaters at intern'iediate offices. This has been accomplished by the transmission of a' single impulse pon the insertion of the plug of a link circuit into the jack of any line when initiating a call thereover.

An object of the present invention is to transmit'a series of impulses from a central oflice over a signaling circuit to distant offices to identity at one of the latter ofiices a particular line which has been taken for use.

Another object is to transmit a series of impulses from acentral office over a signaiing circuit to operate telephone repeaters at intermediate ofiices and to transmit another series of impulses to a distant office to identify thereat a particular line which has been taken "for use at another distant office 7 Another and more specific object 1 e ct the transmission of each series of I pulses simultaneously to the distant am in ermediate t'elephone'repeater offices from l impulse sending mechanism arranged -,.-.trally with respect'to said offices,

L preferred embodiment of the invention 1 strated diagrammatically in Figs, 1 inclusive, of the accompanying draW- inn; the figures being arranged from left- Fig. 5 is a 1] grainmatic view of one of the link circuns employed at each terminating end of the circuit.

to right in their numerical order.

Serial No. 38,124.

conventional illustration of office Y is sufficient for a clear understanding of the invention. Physical transmlsslonlmes A and C and the phantom line B are employed for interconnecting the various offices. Each of the transmission lines has associated there- 'With at offices X, Y and Y, a telephone repeat'er of any Well known filament control type and since these repeaters form no part of the present invention, the same are only conventionally shown. At the central office X, an impulse sending mechanism is provided, the operation of which is initiated by the insertion of the plug of a link circuit into any one of the jacks at either of the terminating or distant offices. The initia operation of this mechanism transmits a series of impulses to all of the offices simultaneously, the function of which is to render effective the telephone repeaters at offices X, Y and Y. At the terminating or distant office Where the call is initiated the operator then actuatcs the ringing key of the link circuit taken for'use, whereupon the impulse mechanism is again ope 'ated to simultaneously transmit a second series of impulses to all of the offices. This second series of impulses operates groups of step ping relays at all of the offices but has no material effect upon apparatus at the dis tant office Where the call is initiated nor at the repeater offices X, Y, and Y, since the repeaters at the latter offices remain effective as long as alink circuitis connected tonne of the transmission lines: However, this second series of impulses operates the mechanism at the other distant oiiice in such manner as to select and operate a signal individual to the line over which the call has b'e'en'initiated. The operator at said distant office, observing the operated condition of this signal. may establish connection with the other distant oiiice, by the insertion of the plug of a link circuit into the jack of a disconnect signal to the operator at the other distant office by the operation of the ringing key of the link circuit which again causes the transmission of an impulse to the impulse sending mechanism at office X to initiate the operation thereof. This operation of the impulse sending mechanism has the effect of operating a supervisory signal in the link circuit at the other distant office associated with the particular line, where upon the operator withdraws the plug of said circuit from its jack.

When the link circuits have been disconnected from the jacks of all of the lines, another initiating impulse is transmitted to office X to start the operation of the impulse sending mechanism thereat. The impulses now transmitted to the various offices operate the apparatus at each of them but the only effect produced is to disable the battery supply circuits for the filaments of the repeaters at offices S, Y and Y. 4

It is to be noted that all slow operating and releasing relays are indicated as such in the drawings by arrows intersecting the armatures of said relays and pointing in the direction that said armatures are slow to move.

It is believed that the invention will now be fully understood from the following detailed description of the operation.

Operator at ofiice W initiates a call one? line circmt A.

Upon the insertion of plug 1 of a link circuit into jack 10 at ofiice W, a circuit is established extending from grounded battery, through the winding of relay 2- associated with the link circuit, the sleeve contacts of plug 1 and jack 10 and the winding. of relay 11 to ground.

Relays 2 and 11 energize in this circuit and upon the closure of the contact of relay 11, a circuit is established from grounded battery, through the winding of relay 18, winding of relay 12 and the contact of relay 11 to ground. Relays 12 and 13 are energized in this circuit but relay 12 is slow to operate and consequently a temporary circuit is established from grounded battery, the alternate contact of relay 13, the left-hand winding of relay l4, and the back contact of relay 12 to ground. Relay 14 is energized and locks in a circuit extending from ground at the contact of relay 16, the contact and right-hand winding of relay 1 1, and the winding of relay 15 to grounded battery. Relay 15 energizes and extends ground from its contact through the left-hand normal contacts of relays 27, 37, 47, 57 and 67 in series and the winding of relay 17 to grounded battery. Upon relay 17 energizing in this circuit, the 30 volt battery 71 is included in the physical lines A and G extending between oflices W and Y, the latter of which is similar in all respects to office Y. This circuit extends from positive pole of battery 71 through the upper winding of polar relay 70, the conductor included in the physical line C, the lower winding of polar relay similar to polar relay 210 at oflioe Y, the normal contact of arelay similar to relay 205 of the latter oflice, the upper winding of the relay similar to relay 210, the conductor included in the line A extending from office Y to cflice W, the lower winding of polar relay and the alternate contact of relay 17 to the negative pole of battery 71. The initiating impulse transmitted by this circuit is repeated at ofiice Y in a manner which will appear in the course of the description and a circuit is thereby completed which includes the windings of polar relay 100 and the left-hand normal contact of relay 108 at office X. said contact shunting the resistance 172. The strength of the current flowing in this circuit and the direction thereof is such that the upper winding of relay 70 is energized to prevent closure of the contact of said relay, but relay 100 operates to close its contact. An impulse is thereby trans mitted to the impulse sending mechanism at the central station X to initiate the operation of this mechanism.

The "closure of the contact of relay 100 establishes a circuit extending from ground through a conducting segment of the continuously operating interrupter 104, the contact of relay 100, the normal contact and winding of relay 103, the normal contact of relay 142 to grounded battery 143. Relay 103 energizes and looks from ground through its inner right-hand alternate contact and winding to battery 1 18. An obvious operating and holding circuit is then established for relay 107. Another interrupter 105 operates in conjunction with the interrupter 104; and these interrupters are so arranged that their conducting segments are alternate ly grounded. After relay 103 has operated and when the interrupter 105 reaches its next grounded segment, a circuit is established from ground at the interrupter 105 through the outer left-hand alternate con tact of relay 103 and the winding of relay 106 to grounded battery. At its left-hand alternat contact, relay 106 establishes an obvious circuit through the left-hand wind ing of relay 108 which thereupon energizes. The first of a series of impulses is now transmitted from oflice X simultaneously in both directions; The transmission of these impulses to ofiice W, will first be described.

The first energization of relay 108 establishes a circuit from the positive pole of a 00 volt battery .71 through the upper winding of relay 100, the conductor included in the line circuit A. extending between oflices X and Y, the windings of a polar relay at the latter ofiice similar to the polar relay .200 at office Y, the conductor included in the line C extending between ofiices Y and X, and the lower Winding of polar relay 100, and the left-hand alternate contact of relay 108 to the negative pole of battery 171. This impulse and succeeding ones are repeated at oilice Y as will appear in the description of the apparatus at ofiice Y The repeated impulse from a source of current such as the 60 volt battery 272 at oflice Y is transmitted over the conductors included With the lines A and 0 extending between otfices Y and TV, through the windings of polar relay 70 and the resistance 72, the battery 71 being also connected to the lines at this time by the energization of relay 17. In the course of the description Where reference is made to the transmission of impulses from otlice r: to ofiice it will be understood tha" in each instance, these impulses are repeated at office Y. The strength and direction of flow of current in the above circuit 0pposing the current from battery 71 such to cause relay 70 to close its contact. circuit is then closed from ground throu" the contact of relay 70, the right-hand nc. mal contact and Winding of relay and the right-hand normal contact of relay (35 to grounded battery. Relay 27 energizes and at its left-hand normal, contact opens the energizing circuit for relay 1'? which releases. Battery 71 is no longer connected to the lines-and polar relay 100 at oliice X therefore releases. Upon the closure or the left-hand alternate contact of relay another circuit cstahlished for relay h it om battery through the Winding of rela; 17 the normal left-hand contacts of relays GT1 5T, 4i and 37, the left-hand a]; ternate contact of relay 2?, the contacts of relays 1 1 and 16 to ground. The energization of relay 17 this time again connects the battery '71 to the lines 3. and

and for a second time effects the 'ization ot polar relay 100 at ottice X. Therefore, immediately after the termination of the first impulse from oflice X and when interrupter 104 reaches a grounded segment another impulse transmitted by the ener giz ation of relay 108 over a circuit extendi'n from grou d through the interrupter 14. the relay 100 the l lit-hand cont of -ela 107 and the l ht-hand Winding of relay 108 to "ounl d battery. T s second imp ,2 9 =1. 4 likewise transmitted to ottice V7 to ene polar relay 70 in the s me manner as pre" I ously described. Referring again to the.

receipt of the first impulse at ofiice under the control of interrupter 105, relay 2?, upon ene.rgizing locks from ground through its middle alternar-i contact and Winding to groin'uled battery at relay and opens the energizing cult of relay 1'? which then releases. Relay 27 also completes a circuit. for relay extending from ground through the right-hand alternate contact of relay 2?, the winding of r lay 28 and the common battery at relay 65, but relay 28, being slow to operate, does not close its contacts until after the first impulse has terminated. When this occurs, relay 2S tahlishes circuit for relay 25 extending from ground at the right-hand contact of relay 28, through the Winding of relay 25 e connnon battery at relay 65. Relay 1 is also slow to operate and therefore does not close its alternate contact until after ten of the second impulse.

. L 4. 1 dc of inter U up .in oyerated to close its contact as pre- .ously stated, whereupon the ground thereat. is extended through the left-hand contact oil relay 23. normal contact of relay 25 and ta Winding of relay 16 to the common battery oi relay 05. Belay 16 energizes in this circuit and upon opening its normal contact disables the locking circuit: for re- 14- and also causes the deenergization 1 1n the remainder of the opie series of stepping relays at u this instance, relay 17 does not 25min and therefore no more iin ill b transmitted from oiiice 1V to to cause the operation of relay 108 i "we control of interrupter 104. Coir scturutln all impulses will now be under sole control of intcrri'ipter 105. llpon ii-u ion of the second impulse. rc-

'- ea and opens the energizing cir- 16 which then restores and The next impulse from ofiice ll under the control again operates polar relay round is extended from the conrelay, through the left-hand lay the alternate contact of relay he right-hand normal contact and winding 0' relay 31 to the common hat L ry at relay 6. Relay 3'? energizes in this (."icuit and locks. through its n iding, and l 1 to ground. I". also c' ses l 'Clllt' tor relay 3S P through the rigl ob v. eing slow to op- (TOLtElCtS until after I Wherel ished for relay extending *om ground. through the right hand contact 0 relay 38 and the winding of relay -35 to the battery at relay 65. Relay 35 is also sloW-to-operate and therefore do's not close its alternate contact immediate upon the closure of the circuit therefor. T he impulses transmitted from office X being now under the sole control of its alternate contact before the next grounded segment of the interrupter 105 is reached. The impulse transmitted when this occurs again operates the polar relay 70 to close its contact, wher upon the ground is extended therethrough to the left-hand contact of relay 28, the alternate contact of relay 25, the left-hand contact of relay 38, the alternate contact of relay the right-hand normal contact and winding of relay 47 to the com- Inon battery at relay 65. By the onergization of relay 35, before this impulse is re ceived, it will be apparent that a circuit will not be established through the wind ing of relay 26 and therefore this relay will fail to operate. Upon the energization of relay 47, the same locks through its wind ing and middle alternate contact to ground and also establishes an energizing circuit for relay 48, extending from ground, through the right-hand alternate contact of relay 47 and the winding of relay 48, to the common battery at relay 65. Relay 48 being slow to operate, does not close its contacts until after the impulse has terminated whereupon a circuit is established for the slow-to-operate relay 45, extending from ground, through the righthand Contact of relay 48, and the winding of relay 45, to the common battery at relay ($5. Relay operates in the same manner relay and closes its alternate contact before the next impulse is transmitted from office X under the control of interrupter 105 and thus prevents the operation of relay 86. When this next impulse is received at oilice 1V, polar relay 70 again operates and the ground at the contact of this relay is then extended over the previously traced circuit as far as the alternate contact of relay 35 and from thence through the lefthand contact of relay 48, the alternate contact of relay 45, the righthand normal con tact and winding of relay 57 to the common battery at relay 65. Relay 57 operates and locks in the same manner as previous similar relays and establishes an obvious energizing circuit for slow-to-operate relay 58 which closes its contacts after the termination of the impulse. This establishes an obvious circuit for slow to operate relay which closes its alternate contact after an interval in the same manner as previous similar relays and thus prevents the operation of relay 46. Therefore when the next impulse is received through the winding of polar relay its contact is closed to extend the ground over the previously described circuit far as the alternate contact of relay 45 and from thence through the lefthand contact of relay 58, the alternate contact of relay 55., the right-hand normal contact and winding of relay 67 to common battery at relay 65. Relay 67 thereupon operates and locks and establishes an obvious circuit for slow to operate relay 68 which closes its contacts after the termination of the impulse to establish an obvious energizing circuit for relay 65. At this period of the operation, relay 142 at office X will be operated to disconnect the batiery 143 from the locking circuit of relay 10 3,

as will be more specifically described here inafter and therefore no more impulses will be transmitted from oilice X, Relay 65, after an interval, energizes and, in open-- ing right-hand contact, removes the conr men battery from the circuits of the series of stepping relays at oflice W, whereupon all of these relays restore to normal. H

lays 11, 12 and 13, however, remain in their operated condition due to theengagement of the plug of a link circuit with jack 10.

The operation of the. series of stepping relays at office X which occurs simultaneously with that of those at oflice VJ will now be described. After the energization of relay 103, in response to the initiating impulse transmitted from oflice W when the plug is inserted into jack 10 and when the first impulse is transmitted from office X by the energization of relays 106 and 108 under the control of interrupter 105, a circuit is established from ground, through the right-hand contact of relay 106, the inner left-hand,

contact of relay 103, the normal contact and Winding of relay 101'and the normal contact of relay 142 to battery 143. Relay 101 energizes and locks in a circuit extending from ground, through its right-hand alter-V nate contact and winding to the battery 143. Relay 101 establishes an energizing circuit for slow-to-operate relay 102 extending from ground, through the left-hand alternate contact of relay 101 and the winding of relay 102 to battery 143. Relay 102, being slow to operate, does not close its contacts until after the termination of the first impulse As will be recalled, the second impulse trans mitted is under the control of the interrupter 104 which closes a circuit through the righthand winding of relay 108. Relay 106 is therefore not energized and the transmission of this second impulse at oflice X has no effect upon the stepping relays thereat. During the transmission of the second impulse under the control of interrupter 104 and when polar relay 100 is energized, a circuit is established from ground, through the interrupter 104, the contact of relay 100, the right-hand contact of relay 107, the junction point 113, the right-hand normal contact, left-hand Winding and left-hand normal contact of differential filament control relay 109, the left-hand contact 01" relay 102, this relay having e ergized after the termination of the first impulse, and the normal contact of relay 1&2 to the battery 1&3. Relay 109 energizes in this circuit and locks in a circuit extending from grounded battery, through its left-hand alternate contact, left-hand winding and middle alternate contact to ground. The closure of the righthand alternate contact of relay 109 connects ground to the battery of the filaments of telephone repeaters RA, RB and RC associated respectively with the lines A, B and C. These repeaters are then rendered effective and remain in this condition as long as a plug is inserted into any one of the jacks at oflice V. From this point in the operation the impulses are under the sole control of interrupter 105. The next impulse establishes a circuit from ground, through the right-hand contact of relay 106, the inner left-hand alternate contact of re lay 103, the right-hand contact of relay 102, the normal contact and winding of relay 111 to battery 1 13. Relay 111 energizes and looks through its winding and right-hand alternate contact to ground and at its lefthand alternate contact establishes an energizing circuit for slow-to-operate relay 112 extending through its winding to battery 143. Relay 112 closes its contact before the next grounded segment of interrupter 105 is reached so that upon the succeeding impulse under the control of this interrupter, the ground from the right-hand contact of relay 106 will be extended through the contacts of relays 102 and 112 and the normal contact and winding of relay 121 to the battery 1 13. Relay 121 energizes and locks in the same manner as previous similar relays and establishes an obvious circuit for slow-to-operate relay 122 which closes its contact after, thetermination of the impulse and before the next grounded segment of interrupter 105 is reached. The next succeeding impulse causes the ground from the right-hand contactof relay 106 to be extended through the alternate contacts of relays 102, 112 and 122, the normal contact and winding of relay 131 to battery 1 13. Relay 131 energizes and locks and-establishes an obvious circuit for slow-to-operate relay 132 which closes its contact after the termination of the impulse so that upon the next succeeding impulse the ground from the right-hand contact of relay 106 is extended through the contacts of relays 102, 112, 122 and 132, the normal contact and winding of relay 141 to grounded battery. Relay 141 energizes and locks in a circuit extending from grounded battery, through the winding oi? this relay, the right-hand alternate contact thereof and the left-hand contact of relay 107 to ground. In energizing, relay 141 establishes an obvious circuit for relay 1 12 which energizes alter the termination of the impulse and before the next grounded segment of relay 105 is reached. The energization of relay 14-2 disconnects the common battery 1 13 from the circuit of the stepping relay 101, 102, etc. and these relays thereupon restore to normal. Relay 142- is also slow to release and sufficient time will therefore elapse tor the release of all of the stepping relays. Relay 142 also disconnects battery 1&3 from the locking circuit of relay 103 which thereupon deenergizes and opens the holding circuit for relay 107. The mechanism at office X is now in normal condition with the exception of the filament-control relay 109.

The-operation at the intermediate telephone repeater oiiice Y which occurs simnltaneously with the operation of the apparatus at oflices W, Y and X during of impulses from the the transmission latter office, will now be described. lVhen the in errupter 105 engages a grounded segment after the initiating impulse has been transmitted from oilice V to oiiice X to operate relay 108 to transmit the first impulse simultaneously in both directions, a circuit is established from the positive pole of battery 171 through the upper winding of polar relay 110, the simplex conduct-or includeu with line A extending from oilicc I to office Y, the upper winding of polar relay 200, the normal contact of relay 201, which shunts the resistance 273, the lower winding of solar relay 200, the

simple conductor iin-lnded with line G extendin from oilice Y to othce X, the lower winding of relay llO and the right-hand alternate contact of relay 108 to the other side oi? battery 171. The direction and strength of current flowing in this circuit causes the polar relay 200- to operate and close its lower contact whereupon an obvious circuit is established for relay 205 which energiz s and connects battery 272 to the windings ot' polar relays 210 and 370 as will be later more fully described. The current in this circuit operates relay 210 to close its upper contact whereupon a circuit is establisher from ground through the upper contact of polar relay 210, the normal contact of relay 3, the normal contact and winding of relay 201, and the left-hand normal contact of relay 213 to cd battery.

ground. zation of relay 201 establishes a circuit for slow-to-operate relay 202 extending from ground through the right-hand alternate contact of relay 201,

the winding of relay 202, and the left-hand contact of relay 243 to grounded battery, but relay 202, being slow to operate, does not close its cont-acts until after the termination of the first impulse transmitted by the operation of relay 108. When this occurs, a circuit is established from ground through the left-hand contact of relay 202, the winding of relay 203, and the left-hand contact of relay 243 to grounded battery. Relay 203 also being slow to operate will not close its alternate contact until after the termination of the next succeeding impulse. Upon the closure of the upper contact of polar relay 210 in response to the next impulse transmitted from office X which, in this instance, is under the control of interrupter 104, a circuit is established from ground through the upper contact of relay 210, the normal contact of relay 203, the right-hand contact of relay 202, the normal contact and left-hand Winding of the differential filament control relay 209 to grounded battery.

Relay 209 operates in this circuit and locks through its left-hand winding and alternate contact to ground. In closing its right-hand alternate contact, a circuit is closed for the battery supply of the filaments of the telephone repeaters RA1, RB-1 and RC1, associated respectively with the lines A, B and C. Relay 209 remains energized in the same manner as difi'erential relay 109 to maintain the battery supply for the telephone repeaters at office Y as long as a plug is inserted in any of the jacks at oflices X and Z. After the termination of the second impulse following which the remaining impulses are under the sole control of interrupter 105, relay 203 operates and prepares a circuit which is closed upon the next closure of the upper contact of polar relay 210 extending from ground thereat through the alternate contact of relay 203, the normal contact of relay 213, the normal rontact and winding of the relay 211, and the left-hand contact of relay 243 to grounded battery. The impulse which last causes the energization of relay 210 and all of the remaining impulses of the series are now under the sole control of interrupter 105. Relay 211 operates in the circuit just traced and locks in the same manner as relay 201 and also establishes a circuit for relay 212 extending from ground through the right-hand alternate contact of relay 211, the winding of relay 212, and the left-hand contact of relay 243 to grounded battery. Relay 212 is slow to operate and does not close its contact until after the impulse has terminated whereupon an obvious circuit is established for relay 213. The transmission of impulses being now under the sole control of the interrupter 105, the relay 213 through its winding to grounded battery at the left-hand contact of relay 243. Relay 222 is also slow to operate and does not close its contact until after the impulse has terminated whereupon an obvious circuit is established for relay 223 which, being slow to operate, closes its alternate contact after an interval to extend the ground from the upper contact of relay 210, with the next operation thereof in response to a succeeding impulse, through the alternate contacts oi? relays 203, 213 and 223, the normal contact of relay 233, the normal contact and winding of relay 231 to grounded battery at the left-hand contact of relay 243. Relay 231 energizes and locks up through its winding and left-hand alternate contact to ground and establishes an obvious circuit for slow-to-operate relay 232 which closes its contact after thetermination of the impulse. A circuit is then established for relay 233, which, due to its slow operation, closes its alternate contact after an interval. Upon the next closure of the upper cont-act of relay 210, the ground thercat, is extended through the alternate contacts of relays 203, 213, 223 and 233, the right-hand contact of relay 243, the normal contact of relay 241 and the left-hand contact of relay 243 to grounded battery. Relay 241 energizes and locks in a circuit from grounded battery, the left-hand contact of relay 243 and the winding and left-hand alternate contact of relay 241 to ground. The energization of relay 241 establishes an obvious circuit for relay 242 which, being slow to operate, does not close its contacts until after the termination of the impulse. By attractin its right-hand contact, relay 242 connects attery through the right-hand winding of relay 209, but this relay is unaffected at this time, since relay 242 does not energize until after the last impulse has been transmitted from office X, the further transmission of impulses being prevented by the release of relay 103 as previouslydescribed. The energization of relay 242 establishes an obvious circuit for relay 243 which, being slow to operate, opens its normal contacts before interrupter 105 reaches another grounded segment, and disconnects the common battery supply from its left- X, will now he described. Upi sure of the lower contact ot poll? the relay 205 is energized as brie to hereinbeiiore to include the 6%) in the lines extending from ol-iic I. lVhen so iuchided, a circuit i from the positive pole of battery E2 the alternate contact of relay 205, t Winding of co r relay 210, the condua to= cluded in. the line C extendinp from Y to oliice Z, the upper winding 0'' relay 3'70, the nonnal contact of r which shunts resistance 372, the low r V 7 v, mg of relay M0, the concur-tor llltl h 1' 2 the line A extending lroui oihce ,J t

Y, and the upper winding or o the negative pole of battery strength and direction of flow of ilil'i a this circuit is such to cause the po, rel ys 21a) and 3'70 to operate and close their upper contacts. The effects of r of the upper contact of relay 210 l been described. The closure oi l 1 of polar relay 3'70 operates to extend th refrom t irough the left-hand n tact and Winding oi? relay t: men battery at the left-hand con lay 365. Relay $2.7 operates in and locks tl'irou its winding and 1t alternate COllllEtCtground. By cloi lett-hand alterir to contact, a cir uit tablished for relay 328 a grounded battery through tli tact of relay 365, the whit and the left-hand alternate 32? to ground. Honey 2, S to operate and does not lose its cont til after the first inr llSQ has tern it llhen this occurs, a circu t is established tor slow-to-operate relay 325 r; ending from the common battery at relay 365 through the Winding of relay 32-5 and the left-hand contact of relay 328 to ground. Relay does not close its alternate contact until after the termination of the next succeeding impulse, At the termination of the first impulse, relay 205 releases to disconnect the battery 272 from the polar relay 370 which thereupon releases to open its con -act. lVhen said next succeeding or 'oud impul: is transmitted Which occurs immediately alter thetermination of the first impulse a id urrelay SH) 328 being norrelay "is co trol of interrupter llll.

ro is egz ende contac' of re ay 328, the normal contact of relay 325, the winding of relay Z3116 to the battery at relay 365. Relay 316 in this circuit no ellect.

but has 1 J fl =c this time, (illGl'gllALu, the second impulse, ltcrnatc contact and thus o ns tl oses ts a y 4 o ie circuit for relay 3.16.

edin r impulses are now under the :ol oi" interrupter 105, The next in1- nsmitted again operates relay 370 the right-hand contact of 28. alternate i "act of r hunt ll 1 and l, relay 537 to tie conrnon battery at relay 365. Relay 2-3 p and locks up in the mans 32'? and at its left-hand altern cl se s a circuit for relay slow to operate, does not close its contacts until tor the termination of this impulse which time relay $338 stablishes an obvious circuit for slow-to-operate relay 335 which closes its alto contact betore interrupter 1.05 r niches the no t grounded segment to transmit another inn pulse. Upon the t-ansmission of this unp ground, is extend d from relay 3;, h the it-harul contact oi ree 1 ct relay 125,

clay 3258, the althe left-hand 1 c ntact and :-:in( iiig o1 inla '1 onion battery at rela Ii ough the allernate contest ol the current is prevented from energizrelay 326. Relay 3 H energizes and 1 1 its up through its Winding and iniuule alt "nate contact to ground. The closure of the l -hanc alternate contact oi? relay Bat? es t lishes a circuit for sloW-to-operate relay 2 t the common battery at relay 3(' Rel l-S operates to close its contacts after the termination or the impulse and in so doing, establishes a circuit for relay EH5 ex- 4 ending; from the coinu'iou battery at clay through the wiuduur of relay 5 to ground at the le'lt-hai'ul contact of relay i-l iS. Relay M5 is also slow to operate and does not close its alternate contact until just previous to the transmission of the next succeeding impulse. At the heginu' of the latter impulse, ground at relay 0,) is extended as preri ,usly described, to the alter contact of relay and from thence through the right-hand contact of rel y 34:8, the alternate contact of relay 315. the leftnand normal contact and Windingof relay to inccted to the common bat- :6 The openmg lay 345 prevents operation of relay 336. Relay 357 operates and locks up in the same manner as described in connection with the other similar relays. A. circuit is then established for slow-to-operatc relay 358 er:- tending from ground at the left-hand alternate contact of relay 357 to battery at relay 365 and after the termination of the impulse, relay 358 closes its contacts. An obvious circuit is then established for slowtooperate relay 355, but this relay is not energized until after an interval and before the next succeeding impulse is transmitted, so that relay 346 will also be prevented from operating on the next impulse. The next operation of the relay 370 in response to the following impulse extends the ground from the contact thereof over the previously described circuit as far as the alternate contact of relay 345 and from thence through the right-hand contact of relay 358, the alternate contact of relay 355, the left-hand normal contact and winding of relay 367 to common battery at relay 365. Relay 367 energizes and locks up through its winding and middle alternate contact and at its lefthand alternate contact establishes a circuit for slow-to-operate relay 368 to the common battery at relay 365. Relay 368 closes its contacts after the termination of this impulse and establishes an obvious circuit for slow-to-operate relay 365. This relay closes its contacts during the passage of the interrupter 105 over a non-grounded segment so as to open the circuit for relay 356 which extends through the right-hand contact of relay 365, thus preventing the operation of the relay 356 at this time. By opening its left-hand contact, relay 365 removes the common battery therefrom and causes the release of the chain of relays including relays 325, 327, 328, etc. The foregoing operations of the series or chains of relays at the various offices are the result of the insertion of the plug 1 of a link circuit into jack 10 at office W, and after all of these relays have been restored to normal, a condition exists wherein the filament control relays 109 and 209 are energized and locked so as to render effective the various telephone repeaters at offices X, Y and Y. Also the relays 11., 12 and 13 at oifice 1V remain energized due to the engagement of the plug in jack 10.

Operator at office'W rings o'ver line A.

With the impulse mechanism at office X and the series of relays at the various offices in normal condition, the operator at office 1V, by depressing the ringing key 3 ot the link circuit connected to line A, establishes a circuit for the ringing-response relay 24 extending from the source of ringing current through the lower alternate contact of ringing key 3, the ring contacts of the plug 1 and jack 10, the left-hand normal contact of relay 19, the right-hand winding of relay 24, the right-hand normal contact of relay 19, the tip contacts of jack 10 and plug 1 and the upper alternate contact of ringing key 3 to ground. Relay 24 locks in an energizing circuit for relay 15 which extends from grounded battery through the winding of relay 15, the leit-hand winding and alter- .n ate contact of relay 24, and the normal contact oi relay 26 to ground. The energization of relay 15 closes a circuit for relay 1.7 extending from ground through the contact of relay 15, the left-hand normal contacts of relays 27, 37, 47, 57 and 67 in series and the winding 01 relay 1.7 to grounded battery. Relay 17 energizes and connects battery 71 through the windings of relay to the condnctors included in the physical lines extending between ofiice W and office Y which, as previously stated, is similar in all respects to the intermediate telephone repeater station Y.

The impulse produced by the connection of battery 7 .1. across the line is repeated at oflice Y, as will later appear in connection with the transmission of an impulse from oilice Z to ofiice X, so as to cause the operation of the polar relay and thereby close a circuit from ground through a conducting segment or the interrupter 104, the contact or": relay 100, the normal contact and winding oi? relay 103 and the normal contact 01' relay 142 to battery 143. Relay 103 ener gizes and locks as previously described and in so doing, establishes a circuit for relay 107. When the interrupter 104 passes from the grounded segment, the interrupter 105 reaches its next grounded segment and an obvious circuit is. thereupon established for,

relay 106 as before. In closing its left-hand contact, relay 106 establishes an energizing circuit for relay 103 through the left-hand winding thereof which thereupon energizes to connect the 60V battery 171 through the windings of relay 100 tothe polar relay at oilice Y" which corresponds to the polar relay 200 at oflice Y. The impulse is here rcpeated by the energization of a relay at office Y similar to relay 205 which thereupon connects the 60V battery corresponding to battery 272 to the physical. lines extending between oifice Y and oflice W. This current, passing through the windings'of relay 70 and the resistance 72 and in opposing the current from battery 71, is of such strength as to cause the operation of relay 70 so as to close its contact. A circuit is then established for relay 27 extending from ground through the contact of relay 70, the righthand normal contact and Winding of relay 27 to the common battery at relay 65. Relay 27 energizes and at its left-hand normal contact opens the energizing circuit for relay 17 which thereupon releases and disconnects the battery 71 from the lines extendin between oflice 1V and Y. thus causing the release of the polar relay 100 at office X. The energization of relay 27 also closes a. circuit for sloi'v-to-operate relay 28 ex'teinling from ground through the right-hand alternate contact of relay 27, winding of relay 28 to thecommon battery at relay 65. Relay 28 however, does not close its contacts until after the termination of the impulse which is transmitted when the interrupter 105 engages a non-grounded segment. lVhen this occurs, relay 28 energizes and at its right-hand contact establishes a circuit for slow-to-operate relay 25 to the comi'non battery at relay 65. Relay 25 operates during a period when the interrupter 105 is passing over a non-grounded segment and the interrupter 104 over a grounded seg ment. Since the'energizing circuit for relay 17 has now been permanently opened upon the energization of relay 27, it will be apparent that battery 71 will. not be connected to the physical lines to transmit another impulse through oflice Y to onice X to operate polar relay 100 and therefore, while the interrupter 104 is on a grounded segment, no circuit will be closed through the right-hand winding of relay 108 as previously described. Therefore. this relay will not operate to transmit another impulse imn'iediat'ely after the first one has been transmitted. It will, therefore, be apparent that the neat impulse from office X is, at this time, under the control of the interrupter 105. Relay 25 operates before the next grounded segment of interrupter 105 is reached so that when this occurs and relay 108 is energized. by the operation of relay 106, another impulse will be transmitted in the same manner as pre viously described to energize the polar relay 70. The ground at the contact of this relay is new extended through the left-hand contact of relay 28, the alternate contact of relay 25, the right-hand normal contact and winding of relay 37 to common battery at rclay 65. Relay 37 energizes and immediately establishes a circuit for relay 1? extending from ground at the normal contact of relay 26 through the alternate contact of relay 2a, the left-hand alternate contact of relay 3?, the left-hand normal contacts of relays 47, 57 and 67 in series and the winding of relay 1? to grounded battery. On this second in.- pulse, therefore, the relay 17 operates to again connect battery 71 to the lines to transmit an impulse to OifiCG X which will again operate polar relay 100 when the interrupter 105 passes onto a non-grounded segment. The interrupter 10 1- now controls the transmission of another or third impulse from ofiice X by the closure of the circuit from ground through the conducting segment thereof, the contact of relay 100, the right-hand contact of relay 10. and the right-hand winding of relay 108 to grounded battery. Relay 108 energizes and connects battery 171 to the lines extending between otlice X and office Y where this impulse is repeated by the relay similar to relay 205 at office Y, and the strength of the current in this circuit is such as to again oppose the battery '11 and cause relay to close its contact. it ill, therefore, be obvious that immediately upon the termination of the impulse controlled by the interrupter 105, another impulse is transmitted from office X by the grounding of a conducting segment of the interrupter 104:. In the meanwhile, relay 37 having energized, the same closes a circuit for relay 38 which extends from ground through the right hand alternate contact of relay 87, the winding of relay 38 t0 grounded battery at relay 65. Relay 38, being slow to operate, does not close its contact until after the termination of the impulse controlled by the interrupter 105. Relay 38, in closing its righthand contact, establishes a circuit for slowto-operate relay 35 to common battery at relay 65, but relay 35, does not close its contact. until after the termination of the impulse transmitted by the interrupter 104-. Therefore, when relay 7 0 is operated by this latter impulse, the ground is extended through. its contact, the left-hand contact of relay 28, the alternate contact of relay the left-hand contact of relay 38, the normal contact of relay 35 and the winding of relay 26 to battery at relay 65. Relay 26 energizes and in so doing opens the previously described lo cking circuit for relay 24, and energizing circuit for relay 15 both of which relays release, the operator having previously released the ringing key 3. The release of relay 15 removes the holding ground for relay 17 which thereupon releases and disconnects the battery 71 from the lines A. and C extending between oflices V, Y and X. After the transmission of the impulse by interrupter 104 and before interrupter 105 reaches the next grounded segment, 2- lay energizes over the circuit previously described for it and thereby opens the energizing circuitfor relay 20 which thereupon releases. Relays'15 and 17 are now released and remain in their normal conditions throughout the remainder of the operations. The last impulse transmitted by the inter rupter 104 is the signaling impulse which determines at office Z, by the operation of relay 319 thereat, the particular line over which the call has been initiated at oiiice as will appear in the description of the operation of the transmission of this impulse from office X to oflice Y and from thence to ofiice Z. From this point of operation. the transmission of impulses from oflice X under the sole control of interrupter 105, since relay 1'? does not again operate to transmit an impulse from oflice V to oflice X.

Upon the next operation of relay 108;- under the control of interrupter 105 and relay 106, relay 70 is again operated as before and the ground on its contact is extended over the previously described path to the alternate contact of relay 35 and from thence through the lett-hand normal contact and winding of relay 4.7 to the common battery at relay 65. Relay 17 energizes and locks up through its winding and middle alternate contact to ground and at the same time establishes through the right-hand alternate contact and winding of relay 4-8 to the common battery at relay 65. Relay 4-8, being slow to operate, does not close its contacts until after the termination of the impulse transmitted from ofiice X, whereupon a circuit is established from ground through the right-hand contact of relay 18 and the winding of relay 4:5 to common battery at relay 65. Relay 15, being slow to operate, closes its alternate contact before the next grounded segment of interrupter 105 is reached so that upon the next impulse transmitted by the energization of relay 1.08, relay 4-5 will have already closed its alternate contact. Therefore, when relay 70 again encrgizes, the ground extended over the previously described circuit and through the lefthand contact of relay 18 will not be transmitted through the winding of relay 36 but will be extended through the alternate contact of relay 45 to the winding of relay 57 and from thence to the common battery at relay 65. Relay 57 operates and locks to establish an obvious circuit for the slow-tooperate relay 58 which closes its contacts after the termination of the impulse. In so doing, an obvious circuit is established for relay 55, and this relay, being slow to operate, closes its alternate contact before the next grounded segment of the interrupter 105 is reached. lherefore, when the next impulse transmitted and relay 70 operand locks up in the same manner as previ-v ous similar relays and establishes an obvi ous circuit tor relay 68 wlnch, being slow to operate, does not close its contacts untilv after the termination of the impulse. When this occurs, the ground at the right-hand contact of relay 68 is extended through the winding of relay to the common battery, thus cstalr-lishing a circuit for this relay.

a circuit from ground Relay 65 also being slow to operate opens its contacts after an interval and before interrupter 105 again reaches a grounded segment. By opening its right-hand contact, relay 65 disconnects the common battery from the circuits previously described for the chain of relays including relays 25, 27, 28, etc., and these relays thereupon restore to normal.

After the first impulse is transmitted to office X by the operation of the ringing key at ofiice W and when relay 106 is energized by the grounding of the first conducting segment of interrupter 105 following the operation and locking of relay 1.03, a circuit is established from ground through the rightliand contact of relay 106, the inner lefthand alternate contact of relay 103, the normal contact and winding of relay 101, the normal contact of relay 142 to battery 143. Relay 101 energizes and initiates the operation of the series of relays 102, 111, 112, etc., in the same manner as previously described with the exception that, upon the energization of relay 102, a circuit is no longer established through the left-hand winding of relay 109, since this relay is now locked. \Vhen relay'1 l2 is energized in this operation, the common battery 143 is disconnected t'rom'the relays of the series and the same then restore to normal.

with the transmission thereof from'ofiice X,

to office W will now be described and it will be understood that this same operation takes efi ect at ol'lice Y. Upon the first energization of relay 108, a circuit is established from the positive pole of battery 171 through the upper winding of relay; 110, the conductor included in the line circuit A extending between oflice X and ofiice. Y, the upper winding of relay 200, the normal contact of relay 204 which shunts the resistance 273, the lower winding of relay 200, the conductor included in the line circuit C extending between oflicc Y and oflice X, the lower winding of relay 110 and the right hand alternate contact of relay 108 to the negative pole of battery 17].. Polar relay 200 operates to close its lower contact to establish the previously described circuit for relay 205 which, in connecting battery 272 to the windings of polar relay 210'to cause this relay to close its upper contact as before described, initiates the operation of the series of relays 202, 203, 311, 312, 313, etc.,

with the same result as previously described with the exception that the energizing circuit for the differential filament control relay 209 is not closed at this time, since the same is now locked. The energization of relay 243 in the operation of this series of relays disconnects the common battery from the relays which thereupon restore to normal.

he effect of the transmission of impulses from office X to office Z will now be described. Upon the operation of the polar relay 200 to close the energizing circuit for relay 205 as previously described, the battery 272 is connected through the windings of the polar relay 210 to the conductors included in the physical lines A and C extending between office Y and office Z and from thence tl'irough the windings of the polar relay 370 and the normal contact of relay 317. The current flowing through this circuit is such as to op erate polar relay 370 to close its contact when the intial impulse is transmitted. A circuit is then established, from ground through the contact of relay 370, the lefthand normal contact and winding of relay 327 and the left-hand normal contact of relay to grounded battery, Relay 327 energizes and, as before, establishes a c' cuit for relay 328 which, however, does not close its contacts until after the termination of the impulse, whereupon a circuit is established for slow-to-operate relay 325 extending from ground at theleft-hand contact of relay 328 through the winding of relay 325 to the common batter-y at relay 365. The transmission of impulses from office X being, at this time, under the sole control of interrupter 105 as described in connection with the series of operations at office W, it will be obvious that relay 325 will operate before the next impulse is transmitted to office Z and therefore, this next i1n pulse will not close a circuit through the normal contact of relay 325 for relay 316 but the ground at the contact of relay 370 upon the operation ofsuch relay in response to this second impulse will be extended through the alternate contact of relay 325, the lefthand normal cont-act and winding of relay 337 to battery at relay 365. It is at this period of the operation at office W that relay 37 is operated to close the circuit for relay 15 which extended through the left-hand winding and alternate contact of relay 24 to ground. at the relay 26, with the result that relay 17 was energized to transmit an impulse to office X to operate the polar relay so that the interrupter 104 would control the transmission of the next impulse by the energization of relay 108 through its right-hand winding. Then the circuit 7 is established through the winding of relay 337, this relay energizes and'locks in the same manner as before and again establishes the energizing circuit for relay 338. which does not close its contact-s, however, until after the termination of the impulse. WVhen this occurs, relay 338 establishes an energizing circuit for relay 335 but this relay does not close its alternate contact until after the next impulse under the control of; interrupter 101 is terminated Thc succeeding impulse controlled by the interrupter 104 is transn'iitted to office Z to energize polar relay 370 and relay 333 now being energized. tlu ground at the contact of relay tended through the right-hand contact relay 323, the alternate contact of rcl the right-hand contact of relay the normal contact of relay 335 arid the winding of relay 326 to battery at relay Relay 326 energizes and establishes a circuit for relay 319 extending from grounded battery through the left-hand contact of relay 365 the winding of relay 319, and the alternate contact of relay 326 to grounll. Relay 319 ener izes and thereu 3011 establishes a circuit extending from the source of ringing current through the alternate contacts of relay 319 and the winding of the ringalown drop or signal controlling relay 349. The

operator at office Z observing the operated condition of this signal device, th reupon inserts the plug 1 of a link circuit into ja k 310 which disconnects the drop 3-1-9 from the source of signaling current 373 and connects the terminals of the line A with the tip and ring conductors of the link circuit. As soon as relay 319 releases, which occurs at the termination of the impulse which encrgized relay 326, the operator at ofiice Z may actuate the listening key 4 of the link circuit and thus connect her telephone set (not shown) to the line and thereby establish connection with the operator at office VJ. Immediately upon the release of relay 326, the slow-tooperate relay 335 is energized in order to extend the ground at polar relay 3T0 upon the reception of the next succeeding impulse at ofiice Z. From this point in the operation, the transmission of impulses from office X is again under the sole control of the interrupter 105, since the relay 17 is now permanently restored to normal as described in connection with "the operation at oflice V. The next impulse received at oflice Z operates the relay 3i? and relays 318, 315, 357, 358, 355, 367, 363 and 3-65 operate in the same manner as previous ly' described when the succeeding impulses are transmitted to office Z. The operation of relay 365 again removes the common battery from the circuits of relays which have been operated at office Z and these relays are again restored to normal.

Upon the insertion of the plug 1 into jack 310, a circuit is established from grounded battery through the winding of relay 2 of the link circuit the sleeve contacts of plug 1 and jack 310 and the winding of. relay 311 to ground. Relay 311 energizes and completes a circuit for relays 312 and 3 13 extending from grounded battery through the windings of relays 313 and 312 and the contact of relay 311to ground. Relay 312, be ing slow to operate, does not immediately close its alternate contact and a circuit is therefore, momentarily established for relay 314; extending from grounded battery through the alternate contact of relay 313, the right-hand winding of relay 314 and the normal contact of relay 312 to ground. Relay 314; energizes and locks up in a circuit extending from ground at the contact of relay 316, the contact and left-hand winding of relay 314, and the winding of relay 315 to grounded battery. Relay 315 energizes in this circuit and prepares a. circuit for relay 317 which is closed after the energization of relay 365 and the consequent release of the series of relays as previously described. This circuit is then extended from ground at the contact of relay 315, the

right-hand normal contacts of relays 327, 337, 3 17, 357 and 367 in series and the wind ing of relay 317 to grounded battery. Relay 317 energizes and establishes a circuit from the positive pole of battery 371, through the upper Winding of polar relay 370, the conductors included in the line circuit C extending between office Z and office Y, the lower winding of polar relay 210, the normal contact of relay 205 which shunts the,

resistance 274, the upper winding of relay 210, the conductors included in the line circuit A extending between office Y and office Z, the lower winding of polar relay 370 and the alternate contact of relay 317 to the negative pole of battery 371. The strength of current and the direction of flow thereof in this circuit operates the polar relay 210 to close its lower contact and cause the energization of relay 204 over an obvious circuit so that the impulse transmitted from office Z will be repeated at office Y over a circuit extending from the positive pole of battery 271 through the upper winding of polar relay 200, the conductors included in the physical line A extending between office Y and office X, the upper winding of polar relay 110, the right-hand normal contact of relay 108 which shunts the resistance 173, the lower winding of polar relay 110, the conductors included in the physical line G extending between office X and office Y, the lower winding of polar relay 200 and the alternate contact of relay 204: to the negative pole of battery 271. This is the circuit previously referred to which produces the repetition of impulses at office Y from office X. The strength and direction of flow of current in this circuit is such as to operate relay 110 to close its contact whereupon a circuit is established for relay 103 extending from ground through a conducting segment of the interrupter 10.4, the contact of relay 110, the normal contact and winding of relay 103, the normal contactof relay 142 to battery'14c3. Relay 103 energizes and looks as before and initiates the ope-ration of the impulse sending mechanism at office X which operates to transmit impulses therefrom. simultaneously in both directions to operate the series of stepping relays at offices V, Y, Y and Z in the same manner as Operator a1? ()f/i06 W initial/63a call to ofiice X 07200 the phantom line B. l

The insertion of the plug 1 of another link circuit at office into jack 20 has no imme 'diate effect upon thesystem since the relays 11, 12 and 13 are already operated by the engagement of the plug in jack 10 and relay 1% will, therefore, not be energized as described in connection with the initiation of a call over line A. However, upon the operator at office V actuating ringing key 3 ofthe link circuit connected to jack 20, relay 34 will operate over a circuit extending from a source of signaling current through the lower alternate contact of key 3, the ring confacts of plug 1 and jack 20, the left-hand normal contact of relay 29, the right-hand winding of relay 3 1, the right-handnormal contact of relay 29, the tip contacts of jack 20 and plug 1 and the upper alternate con tact of ringing key 3 to ground. Relay 34 is responsive to this signaling current and upon energizing, establishes a locking circuit for itself and an energizing circuit for relay 15 extending from grounded battery through the winding of relay 15, the lefthand winding and alternate contact of relay 34, and the normal contact of relay 36 to ground. Relay l5 energizes and establishes a previously described energizing circuit for relay 17 through the left-hand normal contact of relays 27, 37, 47, 57, and 67 in series. Relay17 energizes and con.- nects battery 71 through the windings of polar relay to the conductors included in the physical lines A and C extending be tween oflice W and office Y and through the windings of a polar relay thereat corresponding to the relay 2l0at office Y. The current flowing in this circuit causes the latter relay at office Y to operate in the same manner as previously described in connection with the transmission. of an impulse from office Z and the impulse from oflice V is, therefore, repeated at office X to operate the polar relay 100 as before. Relay 103 is again operated through the interrupter 104 to initiate the transmission of impulsesvfrom ofliee X in both'directions. These impulses are transmitted to oflice Y and Y and the mechanisms thereattogether with that at office X are operated and restored to normal in the same manner as described in connection with the transmission of impulses when the operator at otlice 1V rings over line A to energize relay The first impulse received at office 1V after the operation of the impulse mechanism at the central office has started and which impulse is under the con trol of interrupter 105 operates relay 27 with the same result as previously described, a circuit being established for relay 28 which closes its contacts upon the termination of the first impulse, and establishes a circuit for relay 25. \Vhen relay 27 energizes, the energizing circuit for relay 17 is opened and this relay does not again energize until after the several impulses have been transmitted. T heretore, no impulses will be sent from otiice TV to oflice Z by the energization of relay 108 under the control of interrupter-104 and the transmission of impulses will for a time, be under the sole control. OltiIltQI'lUPtGl 105. vAfter the establishment of the circuit for relay 25 upon the termination of the first impulse from otlice X,the interrupter 1041 will be passing over a grounded segment with no effect upon the system, and the interrupter 105 will be passing over a non-grounded segment, During this interval and before interrupter 105 again reaches a grounded segment, relay 25 energizes so that upon the transmission of the second impulse from oflice X, the ground at relay 70 will not be closed through the winding of relay 16 but will be transferred through the alternate contact of relay 25 to energize relay This relay then causes of. the closure of the circuit for relay 38 which, in closing its contacts after the termination or the second impulse, establishes a circuit for relay and this relay, like relay 25, operates during the interval between the ending of the second impulse and the beginning of the third, so that relay 26 will be prevented from operating. On the third impulse. the ground at relay 70 is extended through the winding of relay 47 to energize the same whereupon a circuit is again established for relay 17 extending from grounded battery through the winding of this relay, the left-hand normal contacts of relays 67 and 57. the left-hand alternate contact of relay 4%, the alternate contact of re y 3 1, and the normal contact of relay to ground. Relay 17 again energizes to cause the transmission of an impulse to oflice Q7. as before which results in the operation of polar relay 100 and the energization of relay 108 through its right-hand winding under the control of interrupter 104. Therefore, immediately upon the ter mination of the third impulse, another or fourth impulse is transmitted from office X to office In the meanwhile, relay 18 's energized and the circuit for relay 15 is .ise trottiofiice X which is under the atter the termination of the last-named control of the interrupter 140-1. Therefore, the ground at the polar relay 70 is extended through the left-hand contact of relay 48, the normal contact of relay 15, the winding of relay 30 to the common battery at relay (35. Relay 36 energizes and removes the locking ground for relays 3st and 15 which thereupon release.

The deenergiz-zation of relay 15 permanently opens the circuit for relay 17 which thereupon releases. At the termination of the impulse, relay t? energizes and opens the circuit for relay which thereupon restores. For the remainder oi the operation, the impluses transmitted from ol'lice. X are again under the sole control of the interrupter 105 so that upon the receipt of the succeeding impulses at oltice V, the relays 57, 58, 55, 67, G8 and will operate in the same manner as described in connection with relays 2 28 and 2 Relays and so will, therefore. remain in their normal conditions and, upon the energization of relay (55, the series of stepping relays at ofiice TV are restored to normal.

Simultaneously with the operation of the various relays at otlice 1V in response to the impulses transmitted from ofiice X, the

mechanism at ofiice Z is operated by the repetition ofthese impulses at oflice Y. The first impulse operates relays 327 and in the same manner as relays 27 and 28 and after the termination of the first impulse and before the receipt of the second impulse, relay 325 operates so as to prevent the operation of relay 316. The second impulse transmitted operates relays and 338 and before the third impulse is t'ansmitted, relay operates to prevent the energization of relay 326. On the third impulse, relay 347 energizes and establishes a circuit tor relay 3 18 which closes its contacts at the termination of this impulse to establish the circuit for relay As before described, this third impulse is under the control of interrupter 105 and the succeeding or fourth impulse is under the control of interrupter 10% due to the energization of lay 17 when relay -17 was operated. The fourth impulse being received at oflice Z immediately after the termination of the preceding impulse causes the operation cl lay 336 over a circuit extending from he common battery at relay 365, tlre win of relay 3 36, the normal contact of r 3&5, the right-hand contact oi? relay 2;, the alternate contact of relay the ri r rand contact of relay 338,'th'e alternate con tact oi 'relay 325, the right-hand contact of relay 328' and the contact of polar relay 370 to ground, Relay 336 operates and closes a circuit for relay 829 extending from ground tl'rrough the contact of relay and the winding of relay 329 to grounded battery at relay 365. The source of signaling current 373 is then extended through the alternate contacts of relay 320 and the wind-- ing of drop 359 which. upon energizing, displays the signal associated with phantom line B at oflice Z to indicate to the operator thereat that a call has been initiated on this line. At the tern'lination oi the ii'i'ipulse which energizes relay 32-16, relay 345 encrgizes and the impulses from cities X now being again under the sole control of the interrupter 105, the relays 357, 358. 155, 367. 368 and 365 are operated in the same man .ner as relays 327, 328 and 325. The energization of relay 365 removes the common bat tery from the series of stepping relays at office Z and these relays then restore tonormal. I

The operator at office Z observing the operated condition of the signal associated with the line'B, inserts plug 1 of another link circuit into jack 820 to open the circuit for drop 359 and by operating her listening key 4 a channel of comn'uinication is established between the operators at office W and office Z. The insertion of the plug into jack 320 does not have the same effect as described in connection with the insertion of the plug into jack 310, since relays 311, 312 and 313 are now operated and an impulse will not be transmitted from oflice Z to oflice X.

Operator at 017500 lV initiates a call to ofice Z over Zine C.

The insertion of a plug of the link circuit lnto pick 30 has no immediate eitlect upon the system at otiice V but upon the operator thereat depressing rmging l ey 3, a circuit 18 established irom source ot signaling current through the lower alternate contact of naling current in this circuit and upon energizing locks in a circuit extending from ground at battery through the winding oi relay 1.5, the left-hand winding and alternate cont-act of relay 4 1 and the normal contact of relay 16 to ground, Relay 15 energizes in this circuit and as before, estaliilishes an energizing circuit for relay 17 which operates again to transmit an initiating impulse to office X to energize relay 103. The impulse mechanism at ofiice X again starts to operate to transmit impulses simultaneously in both directions. These impulses control the series of stepping relays at ottices X, Y and Y as before. The impulses transmitted from oflice X in this instance are under the sole control of the interrupter 105 until the impulse which operates relay 57 at ofiice V is receh cd. Upon the operation of this relay, a circuit is closed for relay 17 extending from grounded battery through the winding of this relay, the left-hand alternate contact of relay 57, the alternate contact of relay 5% and the normal contact oi relay 40 to ground. ttclay 17 operates to again transmit an: impulse to cities X which operates the polar relay 100 so that relay 108 will energize through its right-hand Winding under the control of the interrupter 104. This causes another impulse to be transmitted immediately after the termination oi the impulse which operates relayv 57 and, since relay 58 is, in the meanwhile, energized, the ground from the contact of relay 70 will be extended through the left hand contact oi relay 58, the normal contact of relay 55, which relay is not at this time energized, and the winding of relay 46 to the common battery at relay 65. Relay 46, in energizing, opens the locking circuit for relays 4 1. and 15 which now permanently restore and upon the termination of the impulses, the circuit for relay 40 opened and relay then closes its alternate contact. The succeeding impulses from oitice X are new again under the sole control of interrupter 105 and relays 67, 68 and are operated in the samev manner as described in connection with relays 27, 28 and 25. The cnergization of relay 65 removes the common battery supply'from the series of step ping relays at ofiice W and these relays thereupon restore.

The series of impulses received atoflice Z under the sole control of the interrupter 1.05 operate the groups of stepping relays, at oliice Z in sequence in the same manner as described in connection with relays at otiicc W until the impulse under the control oi the interrupter 104 is transmitted. At this time, relays 357 and 2358 are operated and a circuit is established for relay 3155. Upon the receipt of the last named impulse, the ground at the contact ofrelay 370 is extended through the right-hand contact of relay 358, the normal contact oil? relay 355 and the winding of relay 34.6 to the common battery at relay 315i). Relay 346 energizes and establishes a circuit from said common battery through the winding of relay 339 and the alternate contact of relay 346 to ground. Relay 330 energizes and through its alternate contact, connects the source of signaling current 373 to the winding of drop 309 which controls the signal associated With the line C at office Z. After the termination of the impulse which energizes relay 346, relay closes its alternate contact so that the succeeding impulses which are againnnder the sole control of interrupter 105 operatethe relays 30?. 368 and 365 in the same manner that the relays of the first group of the series are operatcd. The operation of relay 365 removes the common battery supply from the series of stepping relays at ofiice Z and these relays thereupon restore to normal.

The operator at olfice Z observing the actuated condition of the signal associated with line C inserts the plug 1 oi? another link circuit into jack 330 which opens the circuit for drop 369 and upon the operator actuating the listening key -it, she: may then converse with the operator at ofiice 1V.

Operator at ofli'oe Z transmits a disco Meet signal to operator at oflice W.

Upon the completion of the conversation over the line A, the operator at otlice Z actuates the ringing key 3 of the link circuit engaging jack 310 and thereby closes a circuit extending from the source of ringing current through the lower alternate contact of ringing key 3, the ring contacts of plug 1 andjack 310, the right-hand normal contact of relay 319, the left-hand winding of relay 324, the left-hand normal contact of relay 319, the tip contacts of jack 310 and plug 1 and the upper alternate contact of ringing key 3 to ground Relay 32 is responsive to this sigaling currentand in closing its alternate contact, establishes a locking circuit for itself extending from grounded battery through the winding of relay 315, the righthand winding and alternate contact of relay 324, and the. normal contact of relay 326 to ground. Relay 315 ener izes and the stepping relays at office Z being now in normal condi tion, a circuit is established for relay 317 extending from ground, at the contact of relay 315, through the right-hand normal contacts of relays 327, 337, 347, 357 and 367 in series and the winding of relay 317 to grounded battery. Relay 3:17 in energizing connects the battery 371 through the windings of polar relay 370 to the conductors included" in the physical lines A and C extending between oflice Z and ofiice Y and the windings of the polar relay 210. The latter relay rcsponds to the current flowing through this circuit to energize relay 204 as before which, through battery 271, repeats the impulse transmitted from ofiice Z and thereby causes the energization polar relay 110, to cause the operation of relay .103 as in the previous instances. The impulse sending mechanism at office. X now operates in the same manner as previously described to transmit impulses simultaneously therefrom inboth directions. The first impulse trans mittedlunderv the controlof interrupter 105 causes the operationof polar relay 20.0 at oflice Y in. the manner. previously described and through the agency ofthe relay 205., this impulse is repeated by the battery 272 to cause the energization of the polar relay 370 at oiiite Z. The current from battery 272 through the windings of polar relay 210 causes the same to close its upper contact to initiate the operation of the mechanism at oflice Y. The closure or the contact of relay 370 establishes the energizing circuit for relay 327 which, in closing its contacts, prepares a circuit for relay 328 which operates to close its contacts at the termination of the first impulse. A circuit is then prepared for relay 325 as before and this relay, after an interval, closes its alternate contact. The transmission of impulses being at this time under the sole control of the interrupter 105, relay 325 energizes before the second impulse is transmitted and therefore the ground connected to the contact of relay 370 which responds to the second impulse is extended through the alternate contact of relay 325 to energize the relay 337 and relay 316 is therefore prevented from operating. The relay 324. being energized, the energization of relay 337 establishes a circuit for relay 317 extending from grounded battery through the winding of this relay, the right-hand normal contacts of relays 367, 357 and 3&7 in series, the right-hand alternate contact of relay 337, the alternate contact of relay 32 i and the normal contact of relay 326. The operation of relay 327 causes the transmission of another impulse to oliice X to energize the polar relay 110 thereat and relay 108 is then energized through the interrupter 10% to ground. Therefore, immediately upon the termination of the second impulse, another one is transmitted under the control of interrupter 104; and relays 337 and 338 being energized at this time, the ground connected to the contact of relay 370 is extended through the normal contact of relay and the winding of relay 326 to the common battery at relay 365. The energization of relay 320 in this circuit. removes the locking ground from the right-hand winding of relay and this relay with relay 315 there upon release. The release of relay 315 removes the holding ground for relay 317 which thereupon releases. At the termination of the impulse, relay 326 releases and at this time relay 335 closes its alternate contact. The next succeeding impulses transmitted from OffiCi-I X are under the sole control of the interrupter 105 and these inipulses, upon reaching o'fiice Z, operate and restore the remaining groups of stepping relays in the series at said otlice in the same manner as previously described.

The in'ipulses tr i uce X. in the opposite direcnon a repeated at oflice Y to operate the mechanism therea-t and to effect the energization of the polar relay each time an impulse is received at oflice TV. The first impulse received ther energizes relay 27 and at the terzninat" U which closes itscontacts at the termination of the impulse. It is at this time that the transmission of an impulse from office X is under the control of the interrupter 104 and this impulse being received at office \V immediately after the termination of the last impulse causes the energization of relay 26 through the normal contact of relay 35 which does not close its alternate contact until after the terminationof the present impulse. Relay 26, upon energizing, es-

- tablishes a. circuit for relay 19extending from ground through the alternate contact of relay 26 and the winding of relay 19 to the common battery at relay 65. Relay 19 energizes and establishes a circuit from the source of signaling current 73 through the left-hand alternate contact of relay 19, the ring contacts of jack 10 and plug 1, the lower normal contact of ringing'key 3, the left-hand winding of relay 6, condenser 7,

the upper normal contact of ringing key 3,-

the tip contacts of plug 1 and jack 10, and the right-hand alternate contact of relay 19 to the source of current 73. Relay 6 responds to the current flowing in this circuit and locks in a circuit extending from ground through the rightehand winding and upper contact of relay 6. the normal contact of listening key 4 and the contact or relay 2 to grounded battery. Relay 6, in energizing, establishes a circuit for the supervisory lamp 5 extending from ground through the lamp 5, the lower contact of relay 6, the normal contact of listening key 4 and the contact of relay 2 to grounded battery. The operator at oflice' W upon observing the lighted condition of lamp 5 removes the plug from jack 10 and thus terminates the call over the line A. The disconnection of this link circuit from the line A. has no eifect upon relays 11, 12 and 13 the plugs of other link circuits are still engaged with 1acks 9.0 and 30. The succeedlng impulses transnintted from office X againbeing under the sole control of the interrupter 1.05, the

remaining groups of all the stepping relays in the series at office are operated in the same manner as previously described and at the termination of the operation thereof are restored to normal, as before.

by energizes relay 334 through its left-hand winding in the same manneras described in connection with relay 324. The energization of relay 334 again establishes a circuit for relay 315 through the alternate cont-act of relay 334 and the normal contact of relay 336 to ground. Relay 315 in energizing, causes the operation of relay 317 which causes an impulse to be transmitted to office X through office Y' in the same manner as before described to initiate the operation of the impulse mechanism at office X. In the present instance, the first three impulses to be transmitted from office X are under the sole control of the interrupter 105 and cause .the operation of relays 327, 328, 325, 337, 338 and 335 without energizing relays-316 and 326. The third impulse energizes relay 347 and relay 334 being new energized, a circuit is established for relay 317 extending from grounded battery through the winding of said relay, the right-hand normal contacts of relays 367 and 357, the right-hand alternate contact of-relay 334 and the normal contact of relay 336 to ground. Relay 317 again operates to transmit an impulse to office X which energizes polar relay 110 and under the control of interrupter 104, relay 108 is energized through its right-hand winding to transmit a fourth im ulse immediately after the termination of t e previous one. The energization of relay 347 establishes the energizing circuit for relay 348 and this relay closes its contacts at the termination of the third impulse and thereby establishes the circuit for relay 345 which, however, does not close its alternate contact until after the termination of the fourth im pulse. When this fourth impulse-is received at office Z, the ground at the contact of polar relay 370 is extended through the normal contact of relay 345 and the winding of relay 336 to the common battery at relay 365. Relay 336 operates and removes the locking ground for relay 334 and also causes the release of relay 315. The opening of the alternate contact of relay 334 also releases relay 317. At the termination of the fourth impulse, relay 336 releases to open the circuits for relays 334, 315 and 317 and relay 345 closes itsalternate contact so that succeeding impulses received at office Z under the control of interrupter operate to cause the energization of the remaining stepping relays of the series at'oifice Z and after the same are all operated, they are restored to normal as previously described.

The first impulse transmitted from office X to office WV under the sole control of interrupter 105 cause the energization of relays 27, 28, 25, 37, 38, 35, 47 and 48 in the same manner as previously described. 'It is at this time that relay 108 at ofiice X operates under the control of interrupter 104 to trans- 

